The proposed project represents a program of basic research in experimental social psychology. The focus of the research is small group decision-making and problem-solving. Analysis and observation of the processes underlying the production of a group decision or solution are emphasized. Three programs of research will be undertaken: 1. Group decision-making processes. The Social Transition Scheme (STS) model, an extension of Davis' Social Decision Scheme (SDS) model, is proposed. The new approach addresses the group decision-making process directly by following the pattern of opinion change during group deliberation. Initial research attention will be primarily descriptive, examining such questions as the effects of the passage of time, previous shifts in opinion, and group and faction size on STS representations of the group decision-making process. 2. Process losses for problem-solving groups. This portion of the project will extend previous work which demonstrated suboptimal group performance, especially for large groups. Two classes of explanations will be explored, following Steiner's (1972) theoretical model: A. Coordination losses. Several unique steps of the group problem-solving process are identified and research is proposed to examine the importance of these steps for group suboptimality effects. B. Motivation losses. Working from a subjective expected utility model, several bases for low motivation in groups, especially large groups, are identified. The proposed research investigates two of these ("free-rider" and attribution-of-effort effects).